Joint Base Lewis-McChord’s Reserve Airlift Wing stands to lose a total of 172 part- and full-time positions to budget cuts called for in this year’s proposed defense budget, according to an announcement from its commander released this week.

The 446th Reserve Airlift Wing has about 2,200 airmen who work alongside the active-duty 62nd Airlift Wing to support a fleet of 52 C-17 Globemaster III cargo jets.

A wing spokesman could not say if the Air Force would have to use involuntary separations to trim its force if the defense budget passes as proposed.

The budget also would reduce McChord’s fleet. Eight jets would be placed in back-up inventory, Air Force officials said. In addition, the Air Force is reassigning four McChord C-17’s to other bases this year and next to follow through on guidance from the 2013 defense budget.

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All together, about 6,000 airmen serve at McChord between the reserve and active-duty wings. Their mission centers on delivering troops, supplies and humanitarian relief to military operations around the world.

The Air Force Reserve Command is getting the word out about possible cuts to help reservists prepare for reductions that would fall as early as December.

"The vast majority of our people serve locally on a part-time basis, and force structure changes pose significant challenges for Reservists," Air Force Reserve Command Commander Lt. Gen. James F. Jackson said in the news release.

The Air Force has 223 C-17 jets, and JBLM is one of its largest hubs for the plane. It is the only aircraft flown by airmen out of McChord.

Boeing began producing the C-17 in 1991. The company has announced plans to close its Southern California production line now that it has fulfilled its orders.

The jet saw heavy use during the wars in Iraq and Afghanistan. The Air Force announced the fleet’s 2 millionth hour in flight in 2010. The mission was believed to be an airdrop by a JBLM crew flying out of Bagram Air Field in Afghanistan.

In debates about the defense budget so far, lawmakers have not challenged the Air Force’s plans for its C-17 fleet. But some have protested Defense Secretary Chuck Hagel’s effort to retire the A-10 Warthog and a separate proposal to close an airlift wing at Fort Bragg, North Carolina, that supports Army paratroopers in the 82nd Airborne Division.

The defense budget would also retire the Army’s OH-58 Kiowa helicopter, which is prompting the Army to deactivate a Kiowa squadron at JBLM this year.

The probable staffing cuts in the 446th Airlift Wing would eliminate 151 traditional reserve positions and 21 slots for airmen who work full-time for the military. Most cuts would fall in the wing’s operations and maintenance groups.